An optical system provided with an optical element such as an optical fiber, an optical waveguide and an optical transmitter/receiver is known. An example of such an optical system includes an optical multiplexer formed with an optical waveguide having core portions which obliquely intersect each other (please refer to, for example, Patent Publications 1-3 listed later).
FIG. 15 is a schematic view of an optical multiplexer, or an optical system, disclosed in the Patent Publication 1.
This optical multiplexer 200 has an optical waveguide 201 extending in an light-propagating direction A, which optical guide 201 has straight core portions 202a, 202b which obliquely intersect each other. The optical waveguide 201 also has curved extended portions 204a, 204b, 204c formed so as to continue the core portions 202a, 202b in order to optically couple the core portions 202a, 202b to optical fibers 203a, 203b, 203c arranged in the light-propagating direction A. This optical multiplexer 200 is suitable for a case in which the optical fibers 203a, 203b, 203c are coupled to the extended portions 204a, 204b, 204c in optical-array forms 205a, 205b. The optical fibers 203a, 203b, 203c are positioned and supported with a high degree of accuracy relative to the extended portions 204a, 204b, 204c by V-shaped cross-sectional grooves 206 formed on the optical fiber arrays 205a, 205b by means of anisotropic etching.
FIG. 16 is a schematic view of an optical transmitter/receiver which is an optical system disclosed in the Patent Publication 2.
This optical transmitter/receiver 210 has a substrate 211 extending in a light-propagating direction A and an optical waveguide 212 laminated on the substrate 211. The optical waveguide 212 has straight core portions 214a, 214b which obliquely intersect each other at an intersection 213, and an optical filter 215 is disposed at the intersection 213. An optical fiber 216 is optically coupled to one end of the one core portion 214a, while an optical receiver 217 is optically coupled to the other end thereof. Further, an optical transmitter 218 is optically coupled to the other core portion 214b. The substrate 211 is made of a material having a crystal axis, and a crystal-axis direction conforms to a direction of an optical axis 216a of the optical fiber 216. The optical fiber 216 is positioned and supported with a high degree of accuracy relative to the core portion 214a by a V-shaped cross-sectional groove 219 formed on the substrate 211 in the crystal-axis direction by means of anisotropic etching.
FIG. 17 is a schematic view of an optical multiplexer which is an optical system disclosed in the Patent Publication 3.
This optical multiplexer 230 has a substrate 231 extending in a light-propagating direction A and an optical waveguide 232 located on and fixed to the substrate 231. The substrate 231 and the optical waveguide 232 are made separately. The optical waveguide 232 has straight core portions 234a, 234b which obliquely intersect each other at an intersection 233, and an optical filter 235 is disposed at the intersection 233. Optical fibers 236a, 236b are optically coupled to opposite ends of the one core portion 234b, while an optical fiber 236c is optically coupled to one end of the other core portion 234a. The optical fibers 236a, 236b, 236c are positioned and supported on rectangular cross-sectional recesses 237 formed on the substrate 231.
Patent Publication 1: Japanese Patent Laid-open Publication No. 10-332992
Patent Publication 2: Japanese Patent Laid-open Publication No. 2002-90560
Patent Publication 3: Japanese Utility Model Laid-open Publication No. 62-35308